American journal of medical genetics. Part A, Jan 14, 2015
We report a patient with a constitutional missense mutation in SMARCB1, Coffin-Siris Syndrome (CS... more We report a patient with a constitutional missense mutation in SMARCB1, Coffin-Siris Syndrome (CSS), and schwannomatosis. CSS is a rare congenital syndrome with characteristic clinical findings. This thirty-three-year-old man was diagnosed early in life with the constellation of moderate intellectual disability, hypotonia, mild microcephaly, coarse facies, wide mouth with full lips, hypoplasia of the digits, and general hirsutism. At age 26, he was found to have schwannomatosis after presenting with acute spinal cord compression. Blood and tissue analysis of multiple subsequent schwannoma resections revealed a germline missense mutation of SMARCB1, acquired loss of 22q including SMARCB1 and NF2 and mutation of the remaining NF2 wild-type allele-thus completing the four-hit, three-event mechanism associated with schwannomatosis. Variations in five genes have been associated with the Coffin-Siris phenotype: ARID1A, ARID1B, SMARCA4, SMARCB1, and SMARCE1. Of these genes, SMARCB1 has a w...
The chromosomal radiosensitivity of breast cancer patients with a known or putative genetic predi... more The chromosomal radiosensitivity of breast cancer patients with a known or putative genetic predisposition was investigated and compared to a group of healthy women. The chromosomal radiosensitivity was assessed with the G2 and the G0-micronucleus assay. For the G2 assay lymphocytes were irradiated in vitro with a dose of 0.4 Gy (60)Co gamma-rays after 71 h incubation, and chromatid breaks were scored in 50 metaphases. For the micronucleus assay lymphocytes were exposed in vitro to 3.5 Gy (60)Co gamma-rays at a high dose rate or low dose rate. 70 h post-irradiation cultures were arrested and micronuclei were scored in 1000 binucleate cells. The results demonstrated that the group of breast cancer patients with a known or putative genetic predisposition was on the average more radiosensitive than a population of healthy women, and this with the G2 as well as with the high dose rate and low dose rate micronucleus assay. With the G2 assay 43% of the patients were found to be radiosensi...
In Vitro Cellular & Developmental Biology - Animal, 1991
The lens of the eye is one of the rare organs in which tumors do not occur spontaneously. It ther... more The lens of the eye is one of the rare organs in which tumors do not occur spontaneously. It therefore appeared to us that lens cells would not present the background of spontaneous transformation toward malignancy found with many other cell cultures. We have cultured C3H/HeA mouse lens explant (MLE) cells for 70 wk and analyzed changes in malignancy-related phenotypes in function of the number of passages. In vitro, we studied morphology, colony forming efficiency on tissue culture plastic substrate (CFEtc) and in soft agar, population doubling time, saturation density, and invasiveness into precultured chick heart fragments. In vivo, tumorigenicity, invasion, and metastasis were analyzed after injection of cell suspensions subcutaneously and intraperitoneally, after implantation of cells aggregated to collagen sponges under the renal capsule and after implantation of cell aggregates subcutaneously into the tail and into the pinna. The CFEtc, population doubling time, and saturation density increased as the number of passages of culture in vitro increased, but colony formation in soft agar was never observed. MLE cells till passage 16 were not invasive in vitro, but hereafter consistently were found to be invasive. After about 17 passages, corresponding to 25 wk of culture, MLE cells acquired the capacity to form tumors in syngeneic mice. These tumors were invasive but metastases were not observed. We concluded that MLE cells acquired in an apparently spontaneous way a number of malignancy-related phenotypes, without, however, reaching the stage of metastasis.
Nonallelic homologous recombination (NAHR) is the major mechanism underlying recurrent genomic re... more Nonallelic homologous recombination (NAHR) is the major mechanism underlying recurrent genomic rearrangements, including the large deletions at 17q11.2 that cause neurofibromatosis type 1 (NF1). Here, we identify a novel NAHR hotspot, responsible for type-3 NF1 deletions that span 1.0 Mb. Breakpoint clustering within this 1-kb hotspot, termed PRS3, was noted in 10 of 11 known type-3 NF1 deletions. PRS3 is located within the LRRC37B pseudogene of the NF1-REPb and NF1-REPc low-copy repeats. In contrast to other previously characterized NAHR hotspots, PRS3 has not developed on a preexisting allelic homologous recombination hotspot. Furthermore, the variation pattern of PRS3 and its flanking regions is unusual since only NF1-REPc (and not NF1-REPb) is characterized by a high single nucleotide polymorphism (SNP) frequency, suggestive of unidirectional sequence transfer via nonallelic homologous gene conversion (NAHGC). By contrast, the previously described intense NAHR hotspots within the CMT1A-REPs, and the PRS1 and PRS2 hotspots underlying type-1 NF1 deletions, experience frequent bidirectional sequence transfer. PRS3 within NF1-REPc was also found to be involved in NAHGC with the LRRC37B gene, the progenitor locus of the LRRC37B-P duplicons, as indicated by the presence of shared SNPs between these loci. PRS3 therefore represents a weak (and probably evolutionarily rather young) NAHR hotspot with unique properties.
Mutations in the PKHD1 gene are responsible for autosomal recessive polycystic kidney disease (AR... more Mutations in the PKHD1 gene are responsible for autosomal recessive polycystic kidney disease (ARPKD). Using exon scanning by denaturing high-performance liquid chromatography (dHPLC) or bidirectional sequencing of all exons constituting the longest open reading frame, the mutation detection rate reaches approximately 82% and minor lesion mutations include truncating, splice, and missense mutations. The main aim of this study was to screen ARPKD patients in whom only one pathogenic PKHD1 mutation was identified after bidirectional sequencing of the longest open reading frame, for gene copy number alterations by employing multiplex ligation-dependent probe amplification complemented with quantitative real-time polymerase chain reaction. Sixteen ARPKD probands were studied in whom only one clearly pathogenic mutation was previously identified. One patient with a suspected homozygous deletion of the exons 1-37 was also included in this cohort. Three distinct PKHD1 germ-line deletions were identified. Two of these deletions encompassed multiple exons of PKHD1 extending far beyond the 5' and 3' untranslated regions of the gene, and spanning at least 170 and 470 kb, respectively. The third 3.7 kb intragenic deletion affected only exons 20-21 of the PKHD1 gene. Thus, this is the first report presenting analysis of the entire PKHD1 longest open reading frame for gene deletions/duplications in a select cohort of ARPKD patients, in whom previously only one mutation was identified after bidirectional sequencing of the entire longest open reading frame. The data indicate that multiplex ligation-dependent probe amplification is a sensitive and rapid method to identify PKHD1 deletions. Our study demonstrates that dosage analysis will increase the PKHD1 mutation detection rate and should be performed as a complementary assay in patients suspected to have ARPKD in the absence of two clear pathogenic mutations.
American journal of medical genetics. Part A, Jan 14, 2015
We report a patient with a constitutional missense mutation in SMARCB1, Coffin-Siris Syndrome (CS... more We report a patient with a constitutional missense mutation in SMARCB1, Coffin-Siris Syndrome (CSS), and schwannomatosis. CSS is a rare congenital syndrome with characteristic clinical findings. This thirty-three-year-old man was diagnosed early in life with the constellation of moderate intellectual disability, hypotonia, mild microcephaly, coarse facies, wide mouth with full lips, hypoplasia of the digits, and general hirsutism. At age 26, he was found to have schwannomatosis after presenting with acute spinal cord compression. Blood and tissue analysis of multiple subsequent schwannoma resections revealed a germline missense mutation of SMARCB1, acquired loss of 22q including SMARCB1 and NF2 and mutation of the remaining NF2 wild-type allele-thus completing the four-hit, three-event mechanism associated with schwannomatosis. Variations in five genes have been associated with the Coffin-Siris phenotype: ARID1A, ARID1B, SMARCA4, SMARCB1, and SMARCE1. Of these genes, SMARCB1 has a w...
The chromosomal radiosensitivity of breast cancer patients with a known or putative genetic predi... more The chromosomal radiosensitivity of breast cancer patients with a known or putative genetic predisposition was investigated and compared to a group of healthy women. The chromosomal radiosensitivity was assessed with the G2 and the G0-micronucleus assay. For the G2 assay lymphocytes were irradiated in vitro with a dose of 0.4 Gy (60)Co gamma-rays after 71 h incubation, and chromatid breaks were scored in 50 metaphases. For the micronucleus assay lymphocytes were exposed in vitro to 3.5 Gy (60)Co gamma-rays at a high dose rate or low dose rate. 70 h post-irradiation cultures were arrested and micronuclei were scored in 1000 binucleate cells. The results demonstrated that the group of breast cancer patients with a known or putative genetic predisposition was on the average more radiosensitive than a population of healthy women, and this with the G2 as well as with the high dose rate and low dose rate micronucleus assay. With the G2 assay 43% of the patients were found to be radiosensi...
In Vitro Cellular & Developmental Biology - Animal, 1991
The lens of the eye is one of the rare organs in which tumors do not occur spontaneously. It ther... more The lens of the eye is one of the rare organs in which tumors do not occur spontaneously. It therefore appeared to us that lens cells would not present the background of spontaneous transformation toward malignancy found with many other cell cultures. We have cultured C3H/HeA mouse lens explant (MLE) cells for 70 wk and analyzed changes in malignancy-related phenotypes in function of the number of passages. In vitro, we studied morphology, colony forming efficiency on tissue culture plastic substrate (CFEtc) and in soft agar, population doubling time, saturation density, and invasiveness into precultured chick heart fragments. In vivo, tumorigenicity, invasion, and metastasis were analyzed after injection of cell suspensions subcutaneously and intraperitoneally, after implantation of cells aggregated to collagen sponges under the renal capsule and after implantation of cell aggregates subcutaneously into the tail and into the pinna. The CFEtc, population doubling time, and saturation density increased as the number of passages of culture in vitro increased, but colony formation in soft agar was never observed. MLE cells till passage 16 were not invasive in vitro, but hereafter consistently were found to be invasive. After about 17 passages, corresponding to 25 wk of culture, MLE cells acquired the capacity to form tumors in syngeneic mice. These tumors were invasive but metastases were not observed. We concluded that MLE cells acquired in an apparently spontaneous way a number of malignancy-related phenotypes, without, however, reaching the stage of metastasis.
Nonallelic homologous recombination (NAHR) is the major mechanism underlying recurrent genomic re... more Nonallelic homologous recombination (NAHR) is the major mechanism underlying recurrent genomic rearrangements, including the large deletions at 17q11.2 that cause neurofibromatosis type 1 (NF1). Here, we identify a novel NAHR hotspot, responsible for type-3 NF1 deletions that span 1.0 Mb. Breakpoint clustering within this 1-kb hotspot, termed PRS3, was noted in 10 of 11 known type-3 NF1 deletions. PRS3 is located within the LRRC37B pseudogene of the NF1-REPb and NF1-REPc low-copy repeats. In contrast to other previously characterized NAHR hotspots, PRS3 has not developed on a preexisting allelic homologous recombination hotspot. Furthermore, the variation pattern of PRS3 and its flanking regions is unusual since only NF1-REPc (and not NF1-REPb) is characterized by a high single nucleotide polymorphism (SNP) frequency, suggestive of unidirectional sequence transfer via nonallelic homologous gene conversion (NAHGC). By contrast, the previously described intense NAHR hotspots within the CMT1A-REPs, and the PRS1 and PRS2 hotspots underlying type-1 NF1 deletions, experience frequent bidirectional sequence transfer. PRS3 within NF1-REPc was also found to be involved in NAHGC with the LRRC37B gene, the progenitor locus of the LRRC37B-P duplicons, as indicated by the presence of shared SNPs between these loci. PRS3 therefore represents a weak (and probably evolutionarily rather young) NAHR hotspot with unique properties.
Mutations in the PKHD1 gene are responsible for autosomal recessive polycystic kidney disease (AR... more Mutations in the PKHD1 gene are responsible for autosomal recessive polycystic kidney disease (ARPKD). Using exon scanning by denaturing high-performance liquid chromatography (dHPLC) or bidirectional sequencing of all exons constituting the longest open reading frame, the mutation detection rate reaches approximately 82% and minor lesion mutations include truncating, splice, and missense mutations. The main aim of this study was to screen ARPKD patients in whom only one pathogenic PKHD1 mutation was identified after bidirectional sequencing of the longest open reading frame, for gene copy number alterations by employing multiplex ligation-dependent probe amplification complemented with quantitative real-time polymerase chain reaction. Sixteen ARPKD probands were studied in whom only one clearly pathogenic mutation was previously identified. One patient with a suspected homozygous deletion of the exons 1-37 was also included in this cohort. Three distinct PKHD1 germ-line deletions were identified. Two of these deletions encompassed multiple exons of PKHD1 extending far beyond the 5' and 3' untranslated regions of the gene, and spanning at least 170 and 470 kb, respectively. The third 3.7 kb intragenic deletion affected only exons 20-21 of the PKHD1 gene. Thus, this is the first report presenting analysis of the entire PKHD1 longest open reading frame for gene deletions/duplications in a select cohort of ARPKD patients, in whom previously only one mutation was identified after bidirectional sequencing of the entire longest open reading frame. The data indicate that multiplex ligation-dependent probe amplification is a sensitive and rapid method to identify PKHD1 deletions. Our study demonstrates that dosage analysis will increase the PKHD1 mutation detection rate and should be performed as a complementary assay in patients suspected to have ARPKD in the absence of two clear pathogenic mutations.
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Papers by L. Messiaen